摘要： Universal linear optical networks made of on-chip tunable beam splitters and phase shifters form a very promising platform for quantum information processing (QIP). Thanks to their phase stability and reconfigurability, they are robust and enable a variety of quantum information and communication protocols such as quantum teleportation, quantum key distribution, photonic qubit gate protocols and boson sampling. We introduce an 8×8 mode Blass matrix as universal transformation circuit for linear-optical quantum information processing implemented on stoichiometric Si3N4 waveguides. The Si3N4 platform offers the unique combination of high index contrast, ultralow straight-propagation loss and a spectrally wide transparency range. In order to demonstrate that the photonic chip works as a linear-optical processor suited for general-purpose quantum information processing, we program on-chip quantum interference on several beam splitters within the Blass matrix and demonstrate a high visibility interference, obtaining an average fidelity of ~95%. To further demonstrate the flexibility and configurability of our processor we realized an 8-dimensional unitary transformation with single photons in an 8 dimensional rail encoding. Our findings demonstrate the suitability and reliability of a low-loss, integrated linear optical photonic processor based on Si3N4 waveguides. These results show the high potential of Si3N4 for the development of large universal linear optical quantum circuits, which is essential for the progress of quantum information processing.